内蒙古牧区温带草原牧场的著名畜种是三河马和三河牛。[ ]
√
Only when he _____ his homework will he go to play outside. [ ]
A. does
B. will do
C. is doing
D. has done
某企业生产单一产品，该产品的单位产品完全成本为6.3元，单位变动成本为4.5元。若本月产量为1500件，则该产品的固定成本为( )元。
A．9 450
B．6 750
C．2 700
D．3 200
